Your son needs to hire an attorney. If you want to try to get custody then you need an attorney.
Having legal representation is your only hope. I wish I could be more encouraging but since I was not in the courtroom and I did not hear the evidence, I am unable to provide any additional help to you.
I hope that you are able to have a Merry Christmas. I'm sorry that you are going through this.
Where do you go from here? You make a visit to a lawyer who handles CPS cases.
What do you do? You explain the situation in all its painful detail to the lawyer you visit.
You are at a loss? Ask the lawyer you visit with for advice specifi to your situation.
CPS has a poor reputation with many people. However, generally speaking CPS tries to find the best placement they can for a kid. From your description, things have gotten very far down the road with the CPS situation. So, you meeting with a lawyer has now become urgent...do it ASAP.
Answers on Avvo are for general information purposes only and should not be relied upon as legal advice. No attorney / client relationship is created by providing this answer. For specific advice about your situation, you should consult a competent attorney of your choosing.